Method and apparatus for operating row-column matrix panels and devices

ABSTRACT

There is disclosed a method and apparatus for reducing or eliminating differential line aging on gaseous discharge display/memory panels. For a given size N X M grid or point pattern the use or incidence rate of each point is determined by applying normal patterns of characters thereto. The row-column conductor arrays forming matrix cross-points locating a discrete discharge site are shifted so as to assure that the positions in the dot matrix are more evenly utilized.

United States Patent ,[191 Liddle METHOD AND APPARATUS FOR OPERATING ROW-COLUMN MATRIX PANELS AND DEVICES Inventor: David E. Liddle, Toledo, Ohio Assignee: Owens-Illinois, 1nc., Toledo, Ohio Filed: Dec. 11, 1970 Appl. No.: 97,307

US. CL... 315/169 TV, 313/108 B, 340/324 M Int. Cl. H051) 37/00 Field of Search 178/72; 313/108 B;

315/169, 169 TV; 340/324 M References Cited UNITED STATES PATENTS 3,335,220 Wilcox 178/7.2

Bendell 178/72 X 51 Aug. 14, 1973 3,499,167 3/1970 Baker et a1. 315/169 TV 3,513,327

5/1970 Johnson 315/169 TV Primary Examiner-Roy Lake Assistarit Examiner-Lawrence J. Dahl Attorney-Donald K. Wedding and E. J. Holler [5 7 ABSTRACT There is disclosed a method and apparatus for reducing or eliminating differential line aging on gaseous discharge display/memory panels. For a given size N X M grid or point pattern the use or incidence rate of each point is determined by applying normal patterns of characters thereto. The row-column conductor arrays forming matrix cross-points locating a discrete discharge site are shifted so as to assure that the positions in the dot matrix are more evenly utilized.

15 Claims, 4 Drawing; Figures lllllllllllll PAIENIEM: 14 an 3. 753,038 sum 1 BF 2 G) (9 DAVID E. LIDDLE M 7 C) BY Q (a) WMJJ k. (AM/M 5) #64, H0 2 ATTORNEYS '1 METHOD AND APPARATUS FOR OPERATING ROW-COLUMN MATRIX PANELS AND DEVICES BACKGROUND AND SUMMARY OF THE INVENTION The present invention relates to method and apparatus for preventing or minimizing the effect of differen tial line aging in gaseous discharge display/memory panels having transverse row and column conductor arrays supplying operating potentials (sustaining and discharge condition manipulating) to discrete dis charge sites in the panel.

Gaseous discharge display/memory panels to which the invention particularly applies are disclosed in Baker et al. U.S. Pat. No. 3,499,167 and include a thin gaseous discharge medium under pressure bonded by dielectric charge storage members and a pair transverse row and column conductor arrays forming a cross point matrix for supplying operating potentials to discrete discharge sites in the gaseous medium. Such operating potentials include a periodic sustaining potential applied to all conductors in an array and discrete discharges at selected discharge sites (the cross points of the matrix conductor array, e.g., crossing points of column and row conductors) are manipulated on and off by selectively applied. relatively high voltage pulses added to the periodic sustaining potential. The sustaining voltage is of such amplitude that it is insufficient by itself to initiate a discharge at any of the cross points. Such panels have an inherent electrical memory constituted by the storage of charges produced by an initial discharge on the dielectric charge storage members which stored charges constitute electrical potentials opposite the applied potentials which created them and hence terminate the discharge. The potentialdue to store charges, being in the same polarity direction of the succeeding half cycle of applied sustaining potential, aid in initiating the next discharge so that for each cycle of applied sustaining potential therewill be at least two discharges. Since the charges collect rapidly, each discharge lasts for a fraction of a half cycle of applied potential so that light production is a sequence of short flashes. The repetition rate is high enough (for a 50 lcH sustainer there will be 100,000 flashes per second) that the light appears continuous to the human eye. However, once a sequence of discharges at a selected matrix cross point has been initiated, the sequence will be maintained by the sustaining potential. A sequence of discharges once initiated and maintained by the sustaining voltage, may be terminated, e.g., a selected site turned off, in a similar manner by applying an erase signal voltage to selected columns and row conductors locating an on site (one at which a sequence of discharges has been initiated which is to be turned off (termination of the sequence of discharges). The application of such erase or off signal voltage pulses may be in the manner disclosed in Johnson et al. pplication Ser. No. 699,170, filed Jan. 18, 1968. In turning off a discharge site the objective is to modify the amount of charge stored so that the potential or field due to the stored charge is insufficient when added to the field due to applied potential to produce a discharge on the following half cycle.

Gas discharge panels of the type described above require relatively high operating voltages, the magnitude of which depends upon, among other things, the discharge gap or distance between dielectric storage surfaces, gas mixture and pressure, and thickness of the dielectric. For example, with a gas mixture consisting of 99.9 percent neon atoms and 0.1 percent argon atoms at a pressure of from about 0.2 atmospheres to about 1 atmosphere, a discharge gap of 4-6 mils; and a dielectric 1-2 mils thick, the sustaining voltage is in the range of about 250 to 350 volts peak-to-peak at a frequency or period rate of 30 to 50 kH and a high voltage discharge manipulating pulse preferably of about the same amplitude.

In a panel having a 4 X 4 display area and with column conductors being spaced on 30 mil centers with a like spacing for the row conductors there will be approximately l32 column conductors and a like number of row conductors and approximately 17,000 discrete cross points or discrete discharge sites. For discharge site selection purposes, e.g., addressing, each column conductor and each row conductor may use a separate voltage pulse, the initiation of a discharge at a selected site or matrix cross point being determined by the coincidence of voltage pulses on the column and row conductors, half of the voltage on the selected column conductor and half of the high voltage, but of opposite relative polarity, on the row conductor, in the respective arrays in algebraic adding relation to the sustaining voltage.' The periodic sustaining voltage is applied in a similar fashion: one-half is applied to all column conductors and one-half, out of phase, is applied to all row conductors. Alternatively, the row and column pulses may be multiplexed.

As the size of the display area increases, assuming the same degree of resolution (conductors spaced on 30 mil centers) the number of wires to the panel increases proportionately. Likewise, when the degree of resolution is increased by reducing the spacing between conductors (assuming the same size display area) the number of wires to the panel increases in an inversely proportional manner.

When entering or writing alphanumeric (as constrasted with graphic displays) characters forming the textual material displayed by such characters there is provided spacing (optionally one-half the character height) between lines of such textual material, such spacing being the space occupied by one or more row conductor arrays and the discrete discharge sites defined thereby. Moreover, in the matrix of cross points assigned to form characters (denoted herein as a character block of a size N X M where N is the number of discrete horizontal row discharge sites or elemental character points and M is the number of discrete vertical or column discharge sites or elemental character points), the incidence rate or usage rate for specific character points varies depending upon the specific shape of the characters and the frequency of the particular characters in the language being displayed. For example, in English language textual material in a 5 X 7 character matrix, generally the outer perimeter of discharge points has a higher incidence rate point-forpoint than does the next innermost order or circle of discrete sites. Hence, there may be differential line aging in the matrix display, affecting the uniformity of operating characteristics of discrete sites, as well as differcntial aging in the discrete points within a character block. This is true even though the: character blocks are varied on a line basis because of variation in length of words, spacing and the like between the words in the textual material. The present invention is directed to preventing or minimizing the effects of differential line aging in this type of display of alphanumeric characters and it is accomplished by shifting the character blocks one conductor position as each new page of textual material is entered upon the panel. Preferably, after the first page of textual material has been entered upon the panel and the next new page is to be entered, a signal is produced which effects a lateral shifting of the positions of writing information upon the panel at least one column conductor and, simultaneously, a vertical shifting at least one row conductor. Preferably, the shifting is done for therow and column conductors simultaneously. However, since the spaces between lines of textual material receive less use than the spaces between the row conductors, it is preferable to shift more in the direction of the column conductors than in the direction of the row conductors. Accordingly, there is a shifting back and forth between the shift in the direction of the row conductors and then back again to an initial position than there is in the vertical direction along the column conductors. Thus, successive pages of textual material will vary slightly in position or location on the panel so that there is a form of jitter" entered into the writing of pages of textual material upon the panel. This shifting thus improves the average per formance characteristics of the display matrix and avoids the disadvantages of differential line aging in this type display.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other features, aspects and details of the invention will become more apparent from the following specification when considered with the accompanying drawings illustrating a preferred embodiment of the invention wherein:

FIG. 1 is a diagram illustrating a portion of a gas discharge display panel to which the invention is particularly applicable. 1

FIG. 2 illustrates the alphanumeric character use or incidence rate, based on English language textual material, ofa N X M (5 X 7) dot pattern, the numbers in circles being the percent on" time of discharge sites in a character block (N X M large).

FIG. 3 is a simplified diagrammatic illustration of the panel of FIG. 1 and FIG. 3A is a block diagram of circuitry for operating same as well as the circuitry for shifting the N X M pattern in accordance with the invention.

DETAILED DESCRIPTION a. The Display Panel With reference to the drawings, particularly FIG. 1, a gas discharge display panel 10 is constituted by a pair of support plate members 11 and 12, respectively, each of which has on opposing surfaces thereof row and column conductor arrays 13 and 14 which cooperate to define a matrix locating the discharge sites, and a pair of thin dielectric members 15 and 16, respectively, overlying or coated on the conductor arrays and the support plates. Plates 11 and 12 are joined by a spacer sealant means 17 to thus define a thin gas discharge chamber containing a gaseous medium under pressure which produces a copious. supply of charges during discharge at any selected cross point, such charges being collected on and stored within the discrete areas on the surfaces of the dielectric members 15 and I6, respectively.

The gas chamber is under about 10 mils thick (dielectric surface to dielectric surface) and, preferably, the spacing is in the order of 4 to 6 mils. Transversely oriented row and column conductor arrays 13 and 14 are supplied with operating potentials for selectively effecting discharges within the thin gas chamber between selected cross points. The conductors in the arrays are extended to alternate edges of their respective plates for connecting to sources of operating potentials. The gas is one which is under relatively high gas pressure so as to localize the discharges within the chamber and to confine charges produced on discharge to within the volume of gas in which they are created. As set forth in the aforementioned Nolan application, the gas may be a mixture of 99.9 percent atoms of neon and about 0.] percent atoms of argon and at a pressure preferably from about 0.2 atmosphere to about I atmosphere. Other gas compositions and pressures may be used. The outer matrix cross points between the lines labeled BR-l and BR-Z and the lines labeled BC I and BC-2 are maintained in an on state as described in Baker et al. US. Pat. No. 3,499,167, It is for this reason that several conductor lines in these border areas are commonly connected together and to common operating potentials and hence are not directly involved in the practice of the present invention.

Referring now to FIG. 2, the gaseous discharge display/memory panel 10 is shown in a simplified form having 20 row conductors R-l, R-2, R-3, R-20 and 31 column conductors C-1, C-2, C-3, C-3l, the crossing points of the row and column conductors in the panel matrix defining addressable discrete discharge sites, each of which is selectively addressable by application of proper potentials to any selected row conductor and any selected column conductor.

b. The Character Blocks and Usage Rate In an N X M character block where N is the number of discrete horizontal or row discharge sites or elemental character points and M is the number of discrete vertical or column discharge sites or elemental character points the incidence rate or usage rate for specific character points varies. First, once the specific shape of the characters is decided upon, e.g., the specific placements of points of light, or energized discharge points and the size of the N X M character block, the usage rate is determined by the analyzing incidence rate of each specific alphanumeric character in the language (English, French, German, Russian, etc.). A specific example of the results of such an analysis of English language textual material is illustrated in the N X M character block shown in FIG. 2 where N is five and M is seven; there being 35 discrete points available to compose each character, the character block being five (along a row conductor) sites wide and seven sites (along a column conductor) high. The numbers at each position denote percent on time of discharge sites in 1 the character block for a generally average location of textual material within the panel. It will be appreciated that for other languages, non-typical English languages etc., the use or incidence rate may be different than those illustrated.

Thus, the upper left corner site on the first row is on" 39 percent of the time; first site in the second row is on 68 percent of the time and so on. lt will be noted that in general the outer border points are on" a higher percentage of the time than the next inner border points wherein a number of points are on" less than l0 percent of the time. As there are spaces between words and numbers in the textual material there will be a variation in these percentages particularly in the body and near the end of lines of textual material. However, these percentages as shown, illustrate the general incidence rates for an average character block of N X M size where N is five and M is seven.

Since there is usually one space (column conductor) between character blocks for economy in space usage, and since the leftmost column of points has a slightly higher incidence rate than the rightmost column of points, and since the lowest usage or incidence rate appears to be the second from left column, and since the center column has a higher rate than its neighboring column to the right, a shaft of one column conductor to the right of the entire character block aids in achieving a more uniform usage rate for the discharge sites. As noted earlier, the character blocks making up a word, for example, are separated by one column width and since the area occupied high incidence or usage rate leftmost column would be occupied the relatively high use rate right column on a further shift of one more columns, no great advantage is obtained by this further lateral shift so it is not done. However, it is to be clearly understood that should the incidence usage rate be different, then it may be desirable to effect a further lateral shift. Hence, in practicing the method of this invention, one must first determine the relative usage rate of the sites within a character block as described above in connection with FIG. 2. In the case of FIG. 2, observation or simple arithmetical averaging of the percentages of the columns has been used to determine the amount of lateral shift applicable, it being further understood that this shifting is preferably done on entering a new page of text material on the panel.

c. Writing on the Panel In the portion of the panel illustrated in FIG. 1 (circuit connections of which have been deleted from this view) there is shown a portion of a page of text material reading in part: The Quick Brown Fox Jumped. It will be noted that there are three lines (row conductors) between each line of text material, one space or column conductor between each character block in the text material and five column conductors or the space occupied by one block of character information for the space between words in the text material. Moreover, in this illustration, there is one column conductor between the border lines BR-l and BR-2 and BC-l and BC-2, respectively. In some cases there may not be any border lines that are maintained in an on" state, as described above, in which case the first point of light in the character block may begin at the leftmost column conductor and the uppermost row conductor.

Referring now to FIG. 3, the panel is illustrated as one having row conductors, R-l, R-Z, R-3, R-Bt), and 65 column conductors C-l, C-2, C-3, C-65. Each row conductor has its own individual pulser RP-l, RP-Z, RP-3, RP-30. In a similar fashion each column conductor is provided with its own voltage pulsing circuit CP-l, CP-2, CP-3, CP-65, which supply pulse potentials to the column conductors which are of an opposite polarity relative to the pulse potentials supplied by the row pulser circuits RP-l, RP-2, RP-3, RP-30, respectively. The sustainer potentials are applied from the sustaining potential supplies 50 and 51, sustainer supply 50 being of onehalf the magnitude necessary sustaining voltage and applied through the row pulser circuits RP-I, RP-Z, RI -30. In a similar fashion, one-half the sustaining voltage for the column conductors is supplied from sustaining supply source 51 which in this embodiment illustrated is 180 out of phase relative to sustainer supply and is applied through an erasing switch to the column pulsers CP-l, CP-Z, 'CP-S, CP-65.

In order to enter information on to panel 10, operating potential from the row pulsers RP and the column pulsers CP may be supplied in any desired fashion by supplying logic trigger pulses to these pulsing circuits. Such pulsing circuits are well known and a typical example is the transformer type pulsing circuit disclosed in Johnson U.S. Pat. No. 3,5l3,327, it being understood that solid state type pulsing circuits may be used within the context of the present invention.

It should be clearly understood that while there has been disclosed an individual pulsing circuit RP for each of the row conductors and an individual pulsing circuit CP for each of the column conductors, it is clearly within the contemplation of the present invention that the pulsing circuits may be multiplexed in such a way that one pulsing circuit is able to supply pulse potentials to a number of different selected row and column conductors. However, for purposes of simplicity in the present disclosure there has been shown a separate pulser for each circuit. It will be appreciated that these pulser circuits receive low voltage logic pulse signals which are converted or translated to high voltage signals for manipulating the discharge condition of the gas in the panel.

Information to be entered on panel 10' may be supplied from a computer or from a typewriter keyset or any data source 60 of information of an alphanumeric character which it is desirec to write in pages of text material upon panel 10. The data from source 60 is applied in the form coded data signals on six data lines 61 to a character generator 63 (sometimes called read only memory") and which may be a part of source 60, the output from character generator 63 is composed of seven lines 64-1, 64-2, 64-3. 64-7, which, it will be noted, defines the height of the character block and corresponds to M in the N X M matrix. The five column data lines 62 from decode counter 65 step one column in sychronism with clock 66, to be described later. Decode counter counts to six and resets for the next block. It will be noted clock generator 66 supplies pulses to decode counter 65 which supplies five output lines 62 with pulses to step ROM 63 five times (the N in the character block) and the six is for the space between character blocks.

It will be appreciated that the lines 64-1, 64-2, etc. carry pulses corresponding with the character to be ap plied to the panel. Thus, there is illustrated as entered on the panel at text line one The Quick; at text line two Brown Fox and at text line three the letters Jum" and the partial entering of the letter E. In the embodiment illustrated, pulser circuits CP-l, CP-Z, CP-3. CP-65 in this embodiment are each pulsed individually and, in this embodiment, in sequence regardless of whether there are any pulses on any row conductors (a space between words is the same as a character). At that instant, should any of conductors 64-1, 64-7 have a pulse thereon forming a part of a character to be entered upon the panel, the row conductors to which those pulses have been applied via decode and switch circuit 70, discrete discharges are effected in accordance with the application of voltage pulses on the respective row conductors by means of row pulsers RP-l, RP-2, RP-3, RP-30. Thus, when column conductor C-22 was pulsed by column pulser CP-2, only row conductors 21, 25 and 28 have been pulsed by their respective row conductor pulsers. Similarly, when column conductor 23 is pulsed, the same row conductors will be pulsed to form the next part of the letter E. Thus, the information is written upon the panel by pulsing in sequence each column conductor C-l, C-2, C-3 to the last column conductor C-65. Each time there is a pulsing of a column conductor, there is a simultaneous pulsing of selected ones of the seven row conductors. The read only memory 63 takes the data on line 65 from the computer along with the column position information (relative to the text material being entered) lines 62 and converts this into the information to be applied to the row conductors.

cl. Use Averaging Jitter Displacement Referring to FIG. 3a, the jitter displacement or motion is illustrated for one discrete discharge point, as for example, the topmost left-hand corner point located by row conductor R-l and column conductor C-l in FIG. 3. (In FIG. 3A, the row conductors are labeled RA, RB, RC and RD while the column conductors are labeled CA .and CB.) After a full page of textual material has been entered on the panel, and it is desired to enter a new page of textual material (which, it should be understood, may be the same material or an updated version threof) a signal is produced which will effect a shift or displacement in the entering of the information downwardly and to the right to point 2 as located by column conductor CB and row conductor RB. In other words, there is a shift to the right of one column conductor and vertically down of one row conductor so that the information which ordinarily would have been entered at point 1 is now entered at point 2 and the rest of the writing in the panel proceeds from this point. In a similar fashion on the next entry of a full page of information as for example, a form feed and/or erase signal for erasing the information on the panel and entering the new information, there. is a second shift or jittering motion or displacement wherein the information which would have been entered at point 1 is now entered at point 3 as defined by column conductor CA and row conductor RC, all other points having a corresponding displacement. On the next succeeding entry of a new page of textual material, there is again a shift downwardly one row conductor and latterally or to the right one column conductor to point 4 as defined by row conductor RD and column conductor CB. Finally, when a new page of information is to be entered again, the shift is back to point I, as indicated by the .dashed arrow between points 4 and 1. In this way, the jittering displacement or motion of pages of textual information is effected, it being understood that once information is entered or written on the panel it is stationary.

It will be appreciated that instead of introducing a rightward jittering displacement,'the jittering displacement may be initially leftward andthen downward or strictly downward or strictly latterally as desired in accordance with the format for entering the information onto the panel. For example, if a larger border area is left around the panel then there may be more leftward shifting than rightward shifting. By the same token, if there are more or less unused row conductor lines between lines of textual material, there may be more or less vertical shifting, respectivley, as the case may be. In other words, the basic invention involved in the present application is the introduction of a shifting motion, sometimes herein called, jitter motion or displacement, so as to equalize the usage rate for the discrete discharge points in the panel.

Referring again to FIG. 3, the format or scheme of jitter displacement described diagrammatically in connection with FIG. 3A is introduced by using the form feed or bulk erase signal or counterpart thereof. Initially, the first bulk erase signal is applied (and is usually of two cycles of sustainer to effect efficient erasure) to switch 60 to open this switch to thereby remove one-half the sustainer potential from source 51 from all of the column conductors so that any discharge points which have been in a sustained or on state are thereby turned off." Thereafter, the sustainer potential from both source 50 and 51 are applied to the respective row and column conductors by way of the pulser circuits RP for the row conductors and CP for the column conductors. I

In general, it should be noted that the writing rate for entering data upon the panel is controlled essentially by clock 66 and this may be operated in synchronism with a signal (not shown) from data source 60. The system is arranged so that initially on the first page of textual information, the first row line R-1 and the next six row lines (to row conductor No. 7) corresponding to M in the N X M character matrix, are utilized for the entry of information in the manner described herein. However, it will be noted that the next three lines 8, 9 and 10 are included within this group. The pulsers associated with this group of row conductors RP are each provided with the output of an associated AND gate 70-1, 70-2, 70-10, each of which receives a common input on bus conductor 7l-A which, in turn, receives its output from carriage return or textual line signal counter circuit 72. The next group of row conductors, namely, row conductors 11-20 have their respective AND gates 70-10 70-20 connected to receive as a common input output signals appearing on lines 7l-B on carriage return or line counter 72. In a similar fashion, the next and each following or succeeding group of 10 row conductors are connected to receive the signal voltage appearing on output lines 7l-C of carriage return counter 72. The same pattern and format follows throughout the remaining row conductors which may be divided in similar groups of 10 throughout the rest of the panel, it being understood that in the present instance, the groupings by 10's is determined by the height of the characters (MW) and by the spacing between lines of textual material (3). Hence, if the characters were 10 light points high and the spacing between lines of textual material were 5, then the grouping of row conductors would be by 15's. However, it should be noted that in the event it is not desired to shift the character blocks the total spacing between lines, then one line may be omitted or left vacant and no information entered on that particular row conducpreviously entered information from the panel by removing one-half of the sustainer potential, in the embodiment shown, from the column conductors. This same signal is applied to a counter which counts to four. In the embodiment illustrated, there are two outputs from counter 80 and these two outputs are applied on lines 80A and 8013 to decode and switch circuitry 70. The signal code appearing on 80A and 80B would be in the following pattern:

O0,01,l0,andll.

As noted earlier, there are seven input lines 64-1. 64-7 to decode and switch circuitry 70 and 10 output lines numbered in the drawings 0, 1, 2 9. The signal pulses or logic voltages appearing on input terminals 64-1, 64-2, 64-7 are applied to a group of seven of the output lines from decode and switch 70. In other words, there is simply a shifting of the use, one step at a time of the 10 output lines from decode circuit 70 from the -7 lines, to the 1-8. lines to the 2-9 lines, and then back again to the 0-7 output lines from decode and switch circuitry 70. It will be noted that the output leads 0-9 from decode and switch circuitry 70 are each connected individually to one AND gate in the banks of AND gate 70-1. 70-10, 70-11, 70-20 and 70-21 70-30. Thus, when the seven inputs on line 64-1 are applied in whatever pattern they may be in to seven (of ten) output lines from decode and switch circuitry 70, these seven lines will be energized in the same pattern and, according to the logic illustrated in connection with the AND gates 70 and the connections thereto, these seven signals (it being appreciated that there may be a logic pulse or not according to the output from read only memory or character generator 63).

i of the bank of input lines 64-1. 64-7 from output Thus, as the character generator 63 supplies the permutation of pulses on its output conductors 64-1. 64-7, these signals are passed through decode switch and switch circuit 70 to a sequential group of seven of output conductors 0-9 which, in turn, are each individually connected to a corresponding AND gate 70 in the groups of conductors as described above. At the same time, only one of the group of AND gates 70-1. 70-9, 70-10. 70-20, or 70-21. 70-30 have the necessary second logic pulse from counter circuit 72 applied thereto.

Referring now to shift register 90, its application of pulses in sequence to column pulsers CP-l, CP-2, CP-65, is, in general, conventional andexcept for the addition of an additional pulse on alternate bulky erase or sometimes called form feed signals from the data source 60 to signify the entry of a new page of information upon the panel. Thus, the output from clock 66 is applied through gate 96 as input or shifting pulsesto shift register 90. It will be noted that gate 96 has as a second input a singal corresponding to the carriage return signal applied to counter 72. This signal is used to prevent the stepping of shift register 90 and resets the shift register at its initial position, corresponding to the left-hand side of the panel for entry of information thereto (the carriage return signal could also be used simply to reset shift register 90).

It will be apparent that much of the system disclosed herein insofar as the present invention is concerned, is conventional and the main changes in the operation of the system as well as the circuitry to effect. such changes in the addition and use of decode and switch circuitry 70 which per se forms no part of the present invention, and counter circuit 80 and counter circuit 95. With respect to counter circuit 80, its function is to count the form feed or bulk erase signals on each new page of information, to shift the connection (in effect) lines 0-7, to 1-8 or back again to 0-7. The function of counter 95 is tosupply all the form feed signals an additional signal to shift register prior to the entry thereto of information from the clock 66 so that shift register 90, instead of starting to supply an output pulse on output line numbered 1, in effect applies its first output pulse to line 2 thereof on the first form feed or bulk erase signal. In other words, the jitter displacement or motion format diagrammatically illustrated in FIG. 3A is carried out by the apparatus just described.

While the invention has been described in connection with a particular preferred embodiment thereof, it is intended that this embodiment is merely illustrative and not necessarily limitative of this invention since the invention is subject to many changes and modifications without departing from the scope of the invention as set forth in the accompanying claims.

- What is claimed is:

1. A method of preventing differential line aging in a matrix type display panel comprised of a linear column conductor array and a linear row conductor array and on which panel alphanumeric characters are entered by potentials selectively applied to selected rowcolumn conductors respectively defining character blocks which comprises the step of:

simultaneously causing a shifting movement of the display positions all character blocks as a unit at least one conductor position in one of said arrays.

2. The invention defined in claim 1 wherein said step of causing a shifting movement of display positions of character blocks is in the direction of and along said column conductor,

and further including simultaneous shifting movement of said display positions as a unit one conductor position in the direction of and along said row conductors.

3. The invention defined in claim 1 including repeating said step of causing a shifting movement of character block positions at least one further time in the same direction and then returning said character writing to the initial position thereof and repeating the process.

4. A method of improving the average performance characteristics of a display matrix composed of transversely oriented row and column conductor arrays,

wherein alphanumeric characters are written in a p'lurality of N X M cross point positions where N equals the number of row conductors assigned per character position and M equals the number of column conductors assigned per said character positions, comprising the steps of,

determining the incidence rat-e of energized cross points written in said N X M cross points for a normal sequence of alphanumeric character to be displayed within said N X M cross points, and

shifting said N X M cross pointsto at least one set of adjacent cross points along a conductor in said matrix and in a direction so as toestablish a more uniform average use rate for all points in said display matrix.

5. A method of minimizing changes in the average performance characteristics of discrete discharge sites in a crossed row-column conductor gaseous discharge panel wherein the conductors are dielectrically isolated from the gas and wherein alphanumeric textual material is written on the panel a page at a time, which comprises the stcp of introducing a discrete shifting motion of at least one conductor position to each successive page of textual material written on said panel.

6. The invention defined in claim 6 wherein said discrete shifting motion is in a vertical direction.

7. The invention defined in claim wherein said discrete shifting motion is in a horizontal direction.

8. The invention defined in claim 5 wherein said discrete shifting motion has horizontal and vertical components.

9. The invention defined in claim 8 wherein over a series of pages of textual material said discrete shifting motion is zig-zag.

10. In a gas discharge display panel having a rowcolumn conductor cross point matrix for exciting a thin gaseous medium and wherein pages of textual material constituted by alphanumeric characters are entered as successive lines of text material with spacing at least between successive lines of said text material, the improvement comprising means for introducing a discrete displacement of at least one conductor position to each successive page of alphanumeric textual material.

11. The invention defined in claim 10 wherein said discrete displacement is caused to be in a vertical direction.

12. The invention defined in claim 10 wherein said discrete displacement is in a horizontal direction.

13. The invention defined in claim 10 wherein said discrete displacement has both vertical and horizontal components.

14. The invention defined in claim 13 wherein the direction of said horizontal component is reversed for each successive page of textual material.

15. The invention defined in claim 10 wherein said means for introducing a discrete displacement includes a counter means for counting such successive page of textual material by way of counting each full page erase signal. 

1. A method of preventing differential line aging in a matrix type display panel comprised of a linear column conductor array and a linear row conductor array and on which panel alphanumeric characters are entered by potentials selectively applied to selected row-column conductors respectively defining character blocks which comprises the step of: simultaneously causing a shifting movement of the display positions all character blocks as a unit at least one conductor position in one of said arrays.
 2. The invention defined in claim 1 wherein said step of causing a shifting movement of display positions of character blocks is in the direction of and along said column conductor, and further including simultaneous shifting movement of said display positions as a unit one conductor position in the direction of and along said row conductors.
 3. The invention defined in claim 1 including repeating said step of causing a shifting movement of character block positions at least one further time in the same direction and then returning said character writing to the initial position thereof and repeating the process.
 4. A method of improving the average performance characteristics of a display matrix composed of transversely oriented row and column conductor arrays, wherein alphanumeric characters are written in a plurality of N X M cross poinT positions where N equals the number of row conductors assigned per character position and M equals the number of column conductors assigned per said character positions, comprising the steps of, determining the incidence rate of energized cross points written in said N X M cross points for a normal sequence of alphanumeric character to be displayed within said N X M cross points, and shifting said N X M cross points to at least one set of adjacent cross points along a conductor in said matrix and in a direction so as to establish a more uniform average use rate for all points in said display matrix.
 5. A method of minimizing changes in the average performance characteristics of discrete discharge sites in a crossed row-column conductor gaseous discharge panel wherein the conductors are dielectrically isolated from the gas and wherein alphanumeric textual material is written on the panel a page at a time, which comprises the step of introducing a discrete shifting motion of at least one conductor position to each successive page of textual material written on said panel.
 6. The invention defined in claim 6 wherein said discrete shifting motion is in a vertical direction.
 7. The invention defined in claim 5 wherein said discrete shifting motion is in a horizontal direction.
 8. The invention defined in claim 5 wherein said discrete shifting motion has horizontal and vertical components.
 9. The invention defined in claim 8 wherein over a series of pages of textual material said discrete shifting motion is zig-zag.
 10. In a gas discharge display panel having a row-column conductor cross point matrix for exciting a thin gaseous medium and wherein pages of textual material constituted by alphanumeric characters are entered as successive lines of text material with spacing at least between successive lines of said text material, the improvement comprising means for introducing a discrete displacement of at least one conductor position to each successive page of alphanumeric textual material.
 11. The invention defined in claim 10 wherein said discrete displacement is caused to be in a vertical direction.
 12. The invention defined in claim 10 wherein said discrete displacement is in a horizontal direction.
 13. The invention defined in claim 10 wherein said discrete displacement has both vertical and horizontal components.
 14. The invention defined in claim 13 wherein the direction of said horizontal component is reversed for each successive page of textual material.
 15. The invention defined in claim 10 wherein said means for introducing a discrete displacement includes a counter means for counting such successive page of textual material by way of counting each full page erase signal. 